Product Releases

Reference Design for 5W LED Lamps with PFC and Flicker-Free TRIAC Dimming

Wed, 12/15/2010 - 8:21am
Power Integrations today announced a new reference design (RDK-251) for a 5-watt offline LED driver that includes flicker-free TRIAC dimming and single-stage power factor correction (PFC). The reference design is based on Power Integrations’ LNK457DG, a member of the innovative LinkSwitch-PL family of LED driver ICs optimized for compact, non-isolated installations.

The new reference design provides a single constant-current output of 350 mA at a nominal LED string voltage of 15 V. The output current can be reduced using a standard AC mains TRIAC dimmer down to 1% (3 mA) without instability or flickering of the LED array. The supply is compatible with both low-cost, leading-edge dimmers and more sophisticated trailing-edge dimmers. It operates over the universal AC input range (85 VAC to 265 VAC, 47 Hz to 63 Hz) and can withstand an input range of 0 VAC to 300 VAC, improving field reliability and lifetime during line sags and swells.

Power factor is high (>0.9) and input current total harmonic distortion (THD) is low (10% at 115 VAC and
Manufacturability and longevity are also enhanced by the elimination of passive components required in older LED driver designs, including bulky and unreliable high-voltage electrolytic capacitors. LinkSwitch-PL, like its isolated counterpart LinkSwitch-PH, incorporates the controller and high-voltage power MOSFET into a single silicon die, simplifying PCB layout by further minimizing component count and eliminating parasitics between the controller and high-voltage power MOSFET.

The board fits inside a pear-shaped A19 LED replacement lamp with an E26/27 base. RDK-251 contains full power supply specifications, schematic, bill of materials, transformer documentation, printed circuit board layout, and performance data.

LinkSwitch-PL devices are available now in SO-8, eSOP™ and eDIP™ packages. RDK-251 and RDR-251 are available now on the Power Integrations website at


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